CALCULATION OF THERMAL-HYDRAULIC BEHAVIOR OF HORIZONTAL HEAT EXCHANGER WITH PARALLEL TUBES

摘要

The thermal-hydraulic behavior of a horizontal heat exchanger was calculated using RELAP5/Mod 3.2 code. Whole behavior of the heat exchanger was simulated by two parallel condenser tubes with different secondary cooling conditions; saturated boiling flow for a tube at higher elevation and subcooled water flow for the other tube at lower elevation. The extremely different secondary cooling conditions affected the primary flow distribution between the tubes such that the tube inlet flow rate was higher with the secondary cooling capability but not significant to cause flow instability. The existence of non-condensable gas in the primary flow had little effect on the flow distribution at the same secondary condition. Consequently, it was found that a horizontal heat exchanger would have almost uniform flow distribution and stably condense steam even when tubes are under diverse secondary cooling conditions.